This invention relates to a high speed machine for cold forging screws, rivets, and the like hardware, which incorporates a shearing device for shearing the bar stock to be worked.
Known are automatic machines for cold forging screws, rivets, etc., wherein the bar stock is fed gradually into a die carried by a step rotatable head.
The die which receives the bar stock also determines the length of the cylindrical blank to be sheared off the bar. After the bar has been inserted into the die, special shearing devices cut it to the desired length, while the die-carrying head moves through one step to bring the sheared cylindrical blank under the heading punch, which punch is carried by a heavy slide, also caused to reciprocate in synchronism with the back and forth movement of the die-carrying head.
A disadvantage of such conventional machines is their slow rate of operation, due to the high momentum of the punch-carrying slider.
In fact, prior to the shearing operation, the kinetic energy stored up in the slide has to be dissipated, thereafter the shearing can be carried out and the slide re-started, which requires a certain time, again on account of the considerable slide mass.